I was an 8-year old JW kid when that article came out (Mar Vista, CA congregation). That is one of the few articles I remember from that time period. If I remember right, I don't think my parents or I even understood what disfellowshipping was or how it worked. But I do remember that there were a few attendees that always sat in the back.
Richard Kelly tells about this time period in his book "Growing Up in Mama's Club." He tells the story of a fellow who takes over as Company Servant (that's what the CBOE/COBOE was called in those days) that went on a DF rampage soon after he took control of the KH. Kelly describes the practice of having the DFd ones sitting at the back of the Hall. We all considered it as a "place of shame." It was very hard on those who were in a disciplinary situation who really wanted to "come back to the Truth." It was like the medieval practice of putting people in stocks in the center of town or the "scarlet letter" being branded on a person to identify them as sinners.
In most communities a Kingdom Hall would be considered "private property." Trespassers or other unwanted persons could be asked to leave by the JWs. If they refused to leave, the police could be called and the unwelcome guests could be charged with trespassing or disorderly conduct. The fact that a sign says that the "public is invited" to attend does not change the status of the building and its surrounds as private property. It would be similar to inviting everyone in your neighborhood over to your house for a barbeque or to watch the SuperBowl on your widescreen. It is still your private property and you have every right to ask them to leave peacefully. If they refuse to leave, even though they had an invitation, you still have the right to ask them to leave or else you can call the police and have them charged as trespassers or for acting disorderly. A court may later dismiss the charges if no one was injured and no property damage occurred, but at least you got them off the property. JWs and any other church with public meetings can do the same thing.
JV